Atomic Force Microscopy

How AFM Works

Atomic force microscopy is arguably the most versatile and powerful microscopy technology for studying samples at nanoscale. It is versatile because an atomic force microscope can not only image in three-dimensional topography, but it also provides various types of surface measurements to the needs of scientists and engineers. It is powerful because an AFM can generate images at atomic resolution with angstrom scale resolution height information, with minimum sample preparation.

So, how does an AFM work? In this page, we introduce you to the principles of an AFM with an easy to understand video animations. Feel free to share this page with others, and to email us if you have any questions.

AFM Principles

Nano World
'Nano', from the Greek word for 'dwarf', corresponds to a prefix denoting a factor of 10-9. Thus, a nanometer is one billionth of a meter, which is the length scale at which intermolecular force and quantum effect take hold. To put the nanoscale in a more understandable perspective, consider that the size of an atom relative to an apple is similar to the size of an apple relative to the planet Earth! Atomic Force Microscopes (AFMs) give us a window into this nanoscale world.

AFM Principle 
- Surface Sensing
An AFM uses a cantilever with a very sharp tip to scan over a sample surface. As the tip approaches the surface, the close-range, attractive force between the surface and the tip cause the cantilever to deflect towards the surface. However, as the cantilever is brought even closer to the surface, such that the tip makes contact with it, increasingly repulsive force takes over and causes the cantilever to deflect away from the surface.

- Detection Method
A laser beam is used to detect cantilever deflections towards or away from the surface. By reflecting an incident beam off the flat top of the cantilever, any cantilever deflection will cause slight changes in the direction of the reflected beam. A position-sensitive photo diode (PSPD) can be used to track these changes. Thus, if an AFM tip passes over a raised surface feature, the resulting cantilever deflection (and the subsequent change in direction of reflected beam) is recorded by the PSPD.

- Imaging
An AFM images the topography of a sample surface by scanning the cantilever over a region of interest. The raised and lowered features on the sample surface influence the deflection of the cantilever, which is monitored by the PSPD. By using a feedback loop to control the height of the tip above the surface—thus maintaining constant laser position—the AFM can generate an accurate topographic map of the surface features.

Applications of AFM

Materials

Finding new materials with innovative characteristics at the nanoscale have helped guide the development of many industries in the modern age. Such materials have been behind breakthroughs in sectors such as energy, transportation, and life science.

To investigate and characterize innovative nanomaterials, scientists choose Park AFM. Our technical know-how and deep knowledge of various applications helps researchers find a way to examine their samples with unmatched accuracy and productivity.

Characterizing electrical, magnetic, mechanical, and morphological properties of materials are possible with the dedicated operating modes available with Park AFM. With this versatility, our customers can upscale their research capabilities and continue kindling the spirit of innovation and progress brought about by breakthrough nanoscale investigations.

Polymer Applications

Nano Materials Applications

Photonics Applications

Electrical & Electronics

For many, the electronics industry has been a cornerstone in bringing about the prosperity of the modern age. Electronics have completely transformed nearly every facet of day-to-day life, stoking a nearly insatiable societal and economic demand to continuously improve our devices. One of the chief ways to do so is for device companies to produce faster, smaller, cheaper, and more power efficient portable devices. However, the critical dimensions of these products have to be engineered on the order of nanometers. Characterizing electrical properties at nanometer-size, such as electrostatic force interactions, surface charges, conductivity, and electrostatic capacitance directly determines the product quality and performance in each device. Yet, such characterization something that cannot be easily done at an industrial scale with existing tools.

Enter Atomic Force Microscopy (AFM). AFM's high nanoscale resolution and high sensitivity can fulfill the highly challenging requirements of nanoscale electrical property characterization. Park AFM provides industial-quality electrical property detection tools with high productivity to our customers in both research and industry.

Semiconductor Applications

Display Applications

Solar Cell Applications

Manufacturing Review

Semiconductor-based device fabrication and microelectromechanical systems (MEMS) technology have been major sources of the great success enjoyed by the modern high-tech manufacturing industry. Semiconductor-based device fabrication produces logic and vertical memory devices (fin structure, STI, TSV), liquid crystal displays (LCD), light-emitting diodes (LED), organic LED (OLED), and contact image sensors (CIS), etc. MEMS structures provide various photonic applications including the production of wave guide structures. In those industrial device manufacturing processes utilizing both semiconductor-based and MEMS techniques, reviewing (inspection) the correct dimension of device structures and any unintended defects on on them is critical to maximize productivity and cost-efficiency at every step of the whole in-line process.

Recently, as the size of both device structure and defect becomes smaller, down to the range that optical inspection techniques are unable to detect, the need to review at higher and higher sensitivity has been increasing in the manufacturing industries. This has resulted in the adoption of techniques capable of nanometer resolution review such as atomic force microscopy (AFM).

Many industrial researchers and engineers choose Park Automated AFM for their review of aspects of structural geometry such as feature height, pitch, critical dimension (CD), angle, and even sidewalls together with roughness analyses. This is due to their awareness of Park Automated AFM's accurate measurement results, low system noise, high-throughput rate, and minimized tip-to-tip variation from True Non-Contact™ mode AFM imaging technology.

Semiconductor Applications

MEMS Applications

Life Science

Life science has a direct connection in improving the quality of life for all of humanity. Advances in this domain have innumerable applications in the health, pharamaceutical, and agricultural industries. As time marches on, we are pressed by new challenges to better understand the phenomena of life not yet illuminated by the light of science. One such daunting frontier is at the nanoscale. Applying atomic force microscopy (AFM) to life science, researchers are now allowed to begin exploring the darkened mysteries at this border with the unknown.

Researchers using Park AFM in life science can acquire the nanoscale morphology of biological samples accurately and easily. Of particular use is the the force-distance spectroscopy that AFM provides. This technique allows for the characterization of biological materials along such physical properties as stiffness, adhesion, and even its Young's modulus with sub-nN level precision.

Furthermore, Park AFM has developed an innovative in-liquid imaging technology, Scanning Ion Conductance Microscopy (SICM). This technique has enabled researchers to study complicated physiological phenomena in liquid directly, something not possible with conventional microscopes. Not only are physiological biomaterials and live cells able to be imaged with Park SICM, but various pipette-based applications can be integrated into the investigation such as patch clamping for ion channel signal detection, electrochemical reaction analyses, and even nanoinjections or nanobiopsies.

Cell Biology Applications

Micro and Molecular Biology Applications

Electrophysiology Applications

Nanotechnology

Nanotechnology is one of the latest research fields that rely on manipulation of matter on an atomic and molecular scale. Innovation resulting from nanostructure breakthroughs have brought numerous technological advances in both research and industry, contributing to the progress of other research fields as well. These days, using nanostructure fabrication methods in various ways has become standard research in improving product performance irrespective of industry.

To fabricate and characterize nanoscale structures, researchers have been utilizing AFM to find practical solutions since the development of the first commercial AFM from Park Systems. Park Systems’ advanced AFM know-how and a self-developed and especially accurate feedback control system in their AFM products allow their customers to both image and manipulate nano-structures with increased accuracy and with higher productivity.

Nano Fabrication Applications

Nano Lithography Applications